Give a power and a drawback to the user above you.

This may of been made but i put the "drawback" thing in it to give it a little spice, so have at it!

Kind of been done...

https://comicvine.gamespot.com/forums/off-topic-5/say-a-superpower-then-the-person-below-says-your-w-1870723/

Based on Backstabber's name...

Backstabber has the ability to instantly conjure knives, swords, and any other sharp instruments, such as pencils and/or syringes, automatically within the backs of his victims.

Backstabber's only drawback is that each weapon or whatever he chooses to be stabbed into the back of his victims, are coated in his DNA, making it easy for geneticists or law enforcement forensics to figure out the culprit (Backstabber).